Prevent adding Linked Issues and locking fields?

[LaryPeters]

Is there a way to prevent Jira users from adding linked issues to another issue after a certain point in the workflow?

Also, can fields be locked so they cannot be edited after a certain point in the workflow?

Native Jira capability would be good, but plug-ins that can do this would be acceptable.

[Brant Schroeder]

You can remove the field from the "edit" screen in the screen scheme. This removes and ability to field other than in a transition. This means all users will only be able to change the field(s) during a transition.  This would not affect comments or work logs.

For linking I have never done that before.  Found this but don't know if it will meet your needs or not. https://community.atlassian.com/t5/Jira-questions/Can-we-disable-linking-issues-to-an-Issue-when-it-is-closed/qaq-p/324525